function CircleText(option){
	this._init(option);
}
CircleText.prototype = {
	_init: function(option){
		this.x = option.x || 0;
		this.y = option.y || 0;
		this.innerRadius = option.innerRadius || 0;
		this.outerRadius = option.outerRadius || 0;
		this.text = option.text || 'canvas';
		this.innerStyle = option.innerStyle || 'red';
		this.outerStyle = option.outerStyle || 'blue';
		
		this.group = new Konva.Group({
			x: this.x,
			y: this.y
		})
		// 初始化一个内部圆
		var innerCircle = new Konva.Circle({
			x: 0,
			y: 0,
			radius: this.innerRadius,
			fill: this.innerStyle,
			opacity: .8
		})
		this.group.add(innerCircle)
		
		// 初始化一个圆环
		var outerRing = new Konva.Ring({
			x: 0,
			y: 0,
			innerRadius: this.innerRadius,
			outerRadius: this.outerRadius,
			fill: this.outerStyle,
			opacity: .3
		})
		this.group.add(outerRing);
		
		// 初始化一段文字
		var text = new Konva.Text({
			x: 0 - this.outerRadius,
			y: -7,
			width: this.outerRadius * 2,
			fill: '#fff',
			text: this.text,
			align: 'center',
			fontSize: 20,
			fontStyle: 'bold',
		})
		this.group.add(text);
	},
	addToGroupOrLayer: function(arg){
		arg.add(this.group);
	}
}